Arthritis and autoimmune diseases are a major cause of morbidity in the United States. Health disparities have been identified, with higher rates of many of these conditions in American Indian and Alaska Native (AI/AN) populations. Studies of individual forms of arthritis and autoimmune diseases have found high rates of rheumatoid arthritis, lupus, and spondyloarthritis in AI/AN populations. However, these conditions are often neglected as a public health or research priority and some, including osteoarthritis and psoriatic arthritis, have not been studied. Individuals with arthritis or autoimmune diseases are more likely to be hospitalized, and disparities in hospitalization rates have been described in other indigenous populations. Multiple studies in the United States have found disparities in total joint replacement rates in Black vs. White individuals with arthritis, but almost all studies of these disparities exclude the AI/AN population. A systematic population-based investigation of the prevalence, hospitalization rates and outcomes of arthritis and autoimmune diseases, and joint replacement disparities in AI/AN populations is warranted and would add significantly to the literature. To address this understudied health disparity, we propose the following Specific Aims: 1) Determine the prevalence of specific forms of arthritis and autoimmune disease in Alaska Native people statewide; 2) Determine the hospitalization rates and causes of hospitalization for AI/AN compared to non-AI/AN individuals in Alaska with arthritis and autoimmune diseases; and 3) Determine the rate of joint replacements (total knee and total hip) for AI/AN compared to non-AI/AN individuals statewide. It is our expectation, based on available data in AI/AN and other populations, that we will find high rates of most forms of arthritis or autoimmune disease in the Alaska Native population, high hospitalization rates, and low rates of joint replacements. This study is a unique partnership between a researcher in a tribal health organization and the organization's tribal epidemiology center that will leverage existing datasets to address understudied and significant health conditions in the Alaska Native population. We expect this study to add significantly to the literature on health disparities in arthritis and autoimmune diseases.